The National Institute of Standards and Technology (NIST) released its final report on the collapse of the World Trade Center 7 building on Thursday, 6 years after it began its investigation into the collapses of WTC buildings on September 11, 2001.
The symmetrical and rapid collapse of 47-story WTC 7 into its own footprint in what appeared to be an "implosion" like those initiated by demolitions experts to safely bring down buildings has for many years fueled conspiracy theories that the towers were intentionally destroyed, indicating that the attacks of 9/11 were an "inside job."
Adding more intrigue to conspiracy theories, WTC 7 housed offices of the Internal Revenue Service (IRS), the Department of Defense (DOD), the Central Intelligence Agency (CIA), the Office of Emergency Management (OEM), the Securities and Exchange Commission (SEC), and the Secret Service.
The NIST report goes a long way toward explaining how WTC 7 might have collapsed due to fire, but in doing so, ironically, also confirms many of the arguments put forward by conspiracy theorists.
The Federal Emergency Management Agency released a report in 2002 that noted, "The performance of WTC 7 is of significant interest because it appears the collapse was due primarily to fire, rather than any impact damage from the collapsing towers. Prior to September 11, 2001, there was little, if any, record of fire-induced collapse of large fire-protected steel buildings."
The NIST report likewise notes, "This was the first known instance of the total collapse of a tall building primarily due to fires." It adds, "WTC 7 was unlike the WTC towers in many respects. It was a more typical tall building in the design of its structural system. It was not struck by an airplane. The fires in WTC 7 were quite different from those in the towers. Since WTC 7 was not doused with thousands of gallons of jet fuel, large areas of any floor were not ignited simultaneously. Instead the fires in WTC 7 were similar to those that have occurred in several tall buildings where the automatic sprinklers did not function or were not present. These other buildings did not collapse, while WTC 7 succumbed to its fires."
NIST also notes that "the remains of all the WTC buildings were disposed of before congressional action and funding was available for this Investigation to begin", a fact long pointed to as indicative of a cover-up by conspiracy theorists.
The FEMA report speculated as to the possible causes of the collapse, but noted that "confirmation will require additional study and analysis." It stated that "the sequence of the WTC 7 collapse is consistent with an initial failure that occurred internally in the lower floors on the east side of the building." Fires resulted in the building as a result of the impact damage of debris from the collapse of the twin towers. The building's fire suppression system was not sufficient to control the resulting fires on multiple floors.
"In addition," it stated, "the firefighters made the decision fairly early on not to attempt to fight the fires, due in part to the damage to WTC 7 from the collapsing towers." The report reiterated, "It appears that the sprinklers may not have been effective due to the limited water on site, and that the development of the fires was not significantly impeded by the firefighters because manual firefighting efforts were stopped fairly early in the day."
The NIST report similarly states that "The decision not to continue evaluating the building and not to fight the fires was made hours before the building collapsed, so no emergency responders were in or near the building when the collapse occurred."
The FEMA report suggested fuel from tanks for emergency generators might have contributed to the fires in the building. Conspiracy theorists have argued that there is no evidence to support this widely propagated theory and that it is in any event an unlikely explanation for the collapse. FEMA itself acknowledged that this is a "hypothesis based on potential rather than demonstrated fact" and that "there is no physical evidence available" to support the theory.
Indeed, the NIST report states that "fuel oil fires did not play a role in the collapse of WTC 7," confirming what conspiracy theorists have argued: that ruptured fuel lines could not have sustained fires long enough or generated enough heat "to raise the temperature of the critical interior column to the point of significant loss of strength or stiffness." Nor was any smoke that would have resulted from such fires observed.
FEMA noted in its report that the steel structure was fireproofed to 2 inches, but speculated that "During the course of the day, fires may have exposed various structural elements to high temperatures for a sufficient period of time to reduce their strength to the point of causing collapse." NIST contradicts FEMA, reporting thinner layers of fireproofing, and stating that "The installed thickness of the thermal insulation on the floor beams was below that required for unsprinklered or sprinklered buildings, but it is unlikely that the collapse of WTC 7 could have been prevented even if the thickness had been consistent with building code requirements." In other words, WTC 7 was not up to code.
According to the FEMA report, it took 27 seconds from initiation to total collapse. There is no explanation for how they arrived at the starting time, but the report's timeline also notes that from the time video footage shows the first apparent sign of the collapse, the disappearance of the penthouse, it took just seven seconds for the entire structure to fail and completely collapse to the ground. At 186 meters tall, that means WTC 7 collapsed at near free-fall speed.
Conspiracy theorists have long argued that such a rapid collapse demonstrates that demolition explosives must have been used to take out major load-bearing columns. A collapse initiating at one point, they argue, would have resulted in a less symmetrical collapse and remaining intact structure, even if ultimately stressed to the point of failure, would have provided substantial resistance to the collapse such that it would have been more progressive rather than so instantaneous, and taken longer; certainly not near free-fall speed.
The NIST report states that "The probable collapse sequence that caused the global collapse of WTC 7 was initiated by the buckling of a critical interior column in" the northeast of the building.